It seems to me the subjet is the bad behaviour of pupils who bully and harass other children and not the punishment these bullies are to endure.
As in this previous post "On utilise souvent le mot "bully" (as a noun) pour les enfants qui vont à l'école. in that context it is a kid who repeatedly teases, makes fun of, pushes around (either physically or othewise) other kids."
In this context are you sure "brimades" is the right word ? A bit old school (or is your text dated ? but bullying and harassment seem recent bad behaviour at school, don't they ?)or a reference to army, to me.
I'm still searching for the word we would use in French though...
School rules use the words "comportements violents", ou "Les manquements au règlement intérieur de l’école, et, en particulier, toute atteinte à l’intégrité physique ou morale des autres élèves ou des maîtres seront portés à la connaissance des familles."
If some teachers or headmasters are around...